With the rapidly growing interest in wireless communications and Internet connectivity, wireless service providers are competing to capture the market share by offering their customers access to applications that take advantage of both technologies. However, as service providers attempt to widen their customer base, they are discovering inherent difficulties of providing combined voice and data services within circuit-switched networks. These infrastructures cannot meet the enormous demand for bandwidth or support timely, cost-effective delivery of emerging services and applications.
As the wireless market continues to grow at an increasing pace, service providers that rely on circuit-switched networks are facing mounting pressures since their systems cannot sustain increasing bandwidth requirements for new services and applications, and their networks lack the capacity to support the exponential rise in traffic. Such pressures put wireless network service providers at a disadvantage when they compete with other providers that have already begun to migrate to packet-based networks and thus are better prepared to respond quickly to market pressures.
To address these critical challenges, wireless data service providers are deploying next-generation data solutions that not only enable mobility, but also provide a framework for deploying emerging enhanced applications and services. First generation (“1G”) analog wireless systems were initially employed by wireless service providers to provide wireless service. But 1G systems have since been replaced by networks referred to as the second-generation (“2G”) wireless networks that provide increased speeds and capabilities. FIG. 1 is a block diagram illustrating a network architecture 100 that is typically employed in 2G wireless networks.
Referring to FIG. 1, a client terminal 102 communicates over an air interface 104 with a Base Station Controller (“BSC”) 106. The client device 102 may be a code division multiple access (“CDMA”) telephone having no Internet Protocol (“IP”) capability, or a different client device, such as a wireless fax device, for instance. The BSC 106 is in turn coupled via a communication link 108 to a Mobile Switching Center (“MSC”) 110, which serves to connect calls between various points in a network. The communication link 108 may include a Primary Rate Interface (“PRI”) employing a plurality of communication and control channels, which are carried over T1 and/or E1 carrier lines. The MSC 110 is further connected by a voice data link 112 to a Public Switched Telephone Network (“PSTN”) 114, which provides a path through which the MSC 110 may connect calls with a remote MSC and in turn with another client device, or a client device that may access the PSTN 114 via a modem connection 116, such as a client terminal 118 illustrated in FIG. 1.
Further, as illustrated in FIG. 1, the MSC 110 is in turn coupled via a communication link 120 to an Interworking Function (“IWF”) 122. The communication link 120 may include a Frame Relay (“FR”) communication link and/or a PRI, for instance. The IWF 122 is a hardware/software platform that serves as a gateway between a wireless network and a data packet network. The IWF 122 provides access to an IP network 126 and possibly the PSTN 114. The IWF 122 may reside within a service provider's central office or switching center and may connect directly to wireless switches. As illustrated in FIG. 1, the IWF 122 is coupled to the IP network 126 via a communication link 124 including, for example, an IP over Ethernet communication link. The IP network 126 may further provide communication links to other network entities or client devices. As illustrated in FIG. 1, the IP network 126 is coupled via a communication link 128 to a network server 130.
In the network architecture 100 illustrated in FIG. 1, processing of a call on the MSC 110 depends on call setup and management data received from the BSC 106. If the call is identified as a regular voice call, then the MSC 110 may initiate Signaling System 7 (“SS7”) signaling to seize a trunk on an outgoing PRI to the PSTN 114. However, if a call is identified as a data or fax call, the MSC 110 switches the call to the IWF 122 over the FR link 120. Subsequently, the IWF 122 may convert the incoming circuit call into IP data packets that are sent to a destination via the IP network 126. Alternatively, in some deployments, the data packets may be sent back to the MSC 110 that may send the data packets over the PSTN 114 as a regular modem call.
FIG. 2 is a block diagram illustrating typical layered protocol stacks 200 for network devices from the exemplary system 100 illustrated in FIG. 1. Many functions of the network devices may be performed by a protocol. Such functions range from the specification of connectors, addresses of the communications nodes, identification of interfaces, options, flow control, reliability, error reporting, synchronization, etc. A set (also known as suite or stack) of protocols to carry out such functions is defined in FIG. 2 for the network devices. Each protocol in the suite handles one specific aspect of the communication. Lower (network) layers of the suite are primarily designed to provide a connection or path between users to hide details of underlying communications facilities, and upper (or higher) layers of the suite ensure that data is exchanged in correct and understandable form. A transport layer provides the connection between the upper (applications-oriented) layers and the lower (or network-oriented) layers.
The layered protocol stacks in FIG. 2 are described with respect to Internet Protocol suites comprising from lowest-to-highest, a physical, a link, a network, a transport, and an application layer. However, more or fewer layers could also be used, and different layer designations could also be used for the layers in the protocol stacks 200 (e.g., layering based on the seven layer Open System Interconnection (“OSI”) model as developed by the International Organization for Standardization (“ISO”)).
The layered protocol stacks are used to connect network devices to underlying physical transmission medium including a wireless network, a wired network, a wireless area network (“WAN”) or a wired local area network (“LAN”), for instance. However, other computer networks could also be used.
FIG. 2 illustrates a client device 250, such as a personal computer, a telephone 252, the MSC 110, and the IWF 122. As is known in the art, a physical layer defines electrical and physical properties of an underlying transmission medium. The physical layer on the client device 250 includes an RS232 202 that is used to connect the client device 250 to a physical layer including RS232 212 on the telephone 252. The physical link on the telephone 252 may also include a radio link protocol (“RLP”) layer 214 that is used to connect to an RLP layer 224 on the MSC 110. In turn, the physical layer on the MSC 110 may also include a frame relay switched virtual circuit (“FRSVC”) 226 layer including T1 or E1 links for connecting to the physical link including an FRSVC 236 on the IWF 122.
A link layer is used to connect network devices to the underlying physical transmission medium or physical layer. The link layer includes a Point-to-Point Protocol (“PPP”) layer defining an Internet standard for transmission of IP packets over serial lines. The client device 250, the telephone 252, the MSC 110, and the IWF 122 include PPP layers 204, 216, 228, and 238, respectively, as their link layers. The IWF 122 further includes an Ethernet layer 240 (“ETH”) for connecting to an IP network. However, it should be understood that other link layer protocols, such as a Medium Access Control (“MAC”) protocol or IEEE 802.x protocols, could also be used.
Above the link layer, there is a network layer (also called the “Internet Layer” for Internet Protocol suites). The network layer includes an IP layer. Specifically, the client device 250, the telephone 252, the MSC 110, and the IWF 122 include IP layers 206, 218, 230, and 242, respectively.
Above the network layer, there is a transport layer. The transport layer includes a Transmission Control Protocol (“TCP”) layer, for instance. The devices illustrated in FIG. 2 include TCP layers 208, 220, 232, and 244, respectively. The TCP provides a connection-oriented, end-to-end reliable protocol designated to fit into a layered hierarchy of protocols, which support multi-network applications. TCP provides reliable inter-process communication between pairs of network devices attached to distinct but interconnected networks. However, it should be understood that the transport layer may also include a User Datagram Protocol (“UDP”).
Above the transport layer, there is an application layer including application programs. The network devices illustrated in FIG. 2 include application layers (“APP”) 210, 222, 234, and 246, respectively. The application programs provide desired functionality to a network device (e.g., telephony or other communications functionality). For example, application programs may provide voice, video, audio, data or other applications. The application layer protocol may also include application protocol layers. Application protocol layers typically provide a subset of the functionality provided by an application program.
The application layer may include a Dynamic Host Configuration Protocol (“DHCP”) application program or application protocol layer. DHCP is a protocol for passing configuration information such as IP addresses to network devices. The application layer may also include a Service Location Protocol (“SLP”) application program or application protocol layer. As is known in the art, SLP provides a scalable framework for discovery and selection of network services. Additionally, the application layer may also include a Session Initiation Protocol (“SIP”) application program or application protocol layer. SIP is an application layer control (signaling) protocol for creating, modifying and terminating sessions with one or more participants. The application layer may also include an ITU-T H.323 or H.324 application programs or application protocol layers. H.323 is the main family of video conferencing recommendations for IP networks. H.324 is a video conferencing recommendation using Plain-Old-Telephone Service (“POTS”) lines. The application layer may also include a Voice-over-IP (“VoIP”) application program or application protocol layer. VoIP typically comprises several application programs (e.g., H323, SIP, etc.) that convert voice signals into a stream of packets that may then be sent to a packet network.
While today's 2G wireless networks carry voice, limited data applications and provide short messaging services, next generation or third-generation (“3G”) networks offer much greater capacity and significantly higher data rates, enabling service providers to offer enhanced data applications that go beyond traditional wireless e-mail and Internet access. FIG. 3 is a block diagram illustrating a network architecture 300 that is typically used in 3G networks.
Referring to FIG. 3, a client device 302 communicates with a client device 334 on an IP network 318 by means of three devices; a Radio Access Node (“RAN”) 310, a Packet Data Serving Node (“PDSN”) 314 and a home agent node 322. The client device 302 is coupled to the PDSN 314 via an air interface 304, a base station 306 and a communication link 308. The client device 302 may be a CDMA capable telephone having IP capability. In such an embodiment, the client device 302 may transmit PPP packets over the air interface 304 to the radio access node 310 that may encapsulate the received packets and forward them to the PDSN 314 via a communication link 312. The PDSN 314 performs traffic aggregation and acts as a foreign agent for mobile IP functionality.
As illustrated in FIG. 3, the PDSN 314 is further coupled to the IP network 318 via a communication link 316, and the IP network 318 is coupled to the home agent 322 via a communication link 320. The home agent 322 serves as an edge router, directing traffic to mobile client devices via foreign agents located within a service provider's network. Further, as illustrated in FIG. 3, the network 300 includes an Authentication, Authorization and Accounting (“AAA”) server 332, such as a Remote Authentication Dial-In User Service (“RADIUS”) server. As is known in the art, RADIUS enables remote access servers to authenticate users and to authenticate their access to the requested system or service. The AAA server 332 may reside on a visited (foreign) network or a home network. The PDSN 314 may employ the AAA server 332 to perform authentication during establishment of PPP sessions with mobile terminals. The PDSN 314 may also interact with the AAA server 332 during a mobile IP registration process.
Referring back to FIG. 3, the network architecture 300 further includes a media gateway 326 connected to the IP network via a communication link 324, and further connected to a PSTN 330 via a communication link 328. The media gateway 326 converts IP packets to standard voice calls for VoIP calls terminating on the PSTN 330.
As system providers migrate their equipment from 2G to 3G networks, they often need to replace many components and redesign their network architectures. Thus, a need exists for a system and method for supporting 2G to 3G network migration.